The present invention relates generally to outboard drive units and, more particularly, for mounting arrangements for outboard drive units.
Certain known outboard drive units have a leg or underwater body extending down from an underside of a hull bottom and have been mounted in different manners. In one case, the leg is rigidly joined to the engine and extends through an opening in the hull bottom, with a rubber bellows or the like forming a seal between the leg and the edge of the surrounding opening. The pushing forces of the propeller are taken up by the engine and the engine mounting. In the second case, the leg or the underwater housing is fixed to a plate which is screwed securely, or fixed in some other manner, to the bottom of the hull. In this case the entire propeller force can be taken up by the hull or a portion can be taken up by the hull and a portion by the drive unit mounted on the inside of the hull, i.e. the engine and transmission.
U.S. Pat. No. 7,182,657 discloses a third mounting arrangement wherein the boat hull is formed with a vertical well having an internal flange. The boat hull is used with a drive unit having a vertical drive shaft with an underwater housing connected to an upper gear housing, the upper gear housing having a horizontal shaft for connection to an engine. A mounting plate of a drive unit and a screw-down plate are fastened to opposite sides of the flange, with compressible rings between surfaces of the mounting plate and the flange and between surfaces of the screw-down plate and the flange. The rings damp vibrations from the drive to the hull. The propeller forces are transmitted via the mounting plate and the screw-down plate to the flange and the well and, thus, to the boat hull. This permits mounting of the engine inside the hull on relatively soft, vibration-damping pads. A problem with this mounting arrangement is that it does not prevent the drive unit from being mounted to a hull that is of insufficient thickness to support the drive unit. In addition, formation of the well adds to the difficulty of forming the hull.
It is desirable to provide a mounting arrangement for mounting a boat drive to a boat hull that is simple to manufacture. It is also desirable to prevent mounting of boat drives to boat hulls of insufficient thickness.
In accordance with an aspect of the present invention, a mounting arrangement for mounting a boat drive to a boat hull is provided and comprises a mounting collar comprising a first plate having a first opening therein and a first wall extending from a top surface of the first plate around the first opening and defining a first cylinder. The mounting arrangement also comprises a clamping collar comprising a second plate having a second opening therein and a second wall extending from a top surface of the second plate around the second opening and defining a second cylinder, an external shape of at least a top end of the first cylinder substantially matching an internal shape of at least a bottom end of the second cylinder. The first wall of the mounting collar has a first alignment member and the second wall of the clamping collar has a second alignment member, the first alignment member and the second alignment member being positioned so that, when the first plate is mounted against an exterior of the boat hull and the second plate is mounted against an interior of the boat hull with the first cylinder received in the second cylinder, the first alignment member and the second alignment member align when the boat hull is at least a first predetermined thickness.
In accordance with another aspect of the present invention, a boat comprises a hull, the hull having a wall and an opening extending through the wall, a drive unit comprising a mounting plate having an upwardly facing, substantially frustoconical mounting surface, a hold down plate having a downwardly facing, substantially frustoconical mounting surface, and a mounting arrangement for mounting the boat drive to the boat hull. The mounting arrangement comprises a mounting collar comprising a first plate having a first opening therein and a first wall extending from a top surface of the first plate around the first opening and defining a first cylinder, the first wall comprises a peripheral flange extending around an inside of the wall, a clamping collar comprising a second plate having a second opening therein and a second wall extending from a top surface of the second plate around the second opening and defining a second cylinder, an external shape of at least a top end of the first cylinder substantially matching an internal shape of at least a bottom end of the second cylinder. The peripheral flange comprises a downwardly facing, substantially frustoconical mounting surface arranged to face the upwardly facing, substantially frustoconical mounting surface of the mounting plate of the drive unit, and an upwardly facing, substantially frustoconical mounting surface arranged to face the downwardly facing, substantially frustoconical mounting surface of the hold down plate.
In accordance with yet another aspect of the present invention, a method of mounting a drive unit to a hull of a boat is provided. According to the method, a mounting collar comprising a first plate having a first opening therein and a first wall extending from a top surface of the first plate around the first opening and defining a first cylinder, the first wall comprising a peripheral flange extending around an inside of the wall, is positioned so that the top of the first plate faces a bottom of the hull and so that the first wall extends upwardly through an opening in a wall of the hull. A clamping collar comprising a second plate having a second opening therein and a second wall extending from a top surface of the second plate around the second opening and defining a second cylinder, an external shape of at least a top end of the first cylinder substantially matching an internal shape of at least a bottom end of the second cylinder, is positioned so that a bottom of the second plate faces a top of the hull and the first cylinder is at least partially received in the second cylinder. A mounting plate of the drive unit is positioned so that an upwardly facing, substantially frustoconical mounting surface of the mounting plate faces a downwardly facing, substantially frustoconical mounting surface of the peripheral flange. A hold down plate is positioned so that a downwardly facing, substantially frustoconical mounting surface of the hold down plate faces the upwardly facing substantially frustoconical mounting surface of the peripheral flange. The hold down plate is fastened to the mounting plate via fasteners.